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Full text of "Flora Indica Vol-I"

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INTRODUCTORY   ESSAY.                                101
and, though fully representing the Flora of the Polar regions,
contains so many types that are foreign to them (as Gentiana,
Ephedra, Valerianea, Corydalis], and some which are even
rare in Siberia, that it must rather be considered as a conti-
nuation of the Alpine Flora of Europe than a representation
of that of the Arctic zone. It displays one remarkable fea-
ture throughout its whole extent, a comparative paucity of
Cryptogamic plants; and it is especially poor in those luxuriant
mosses of tall growth and succulent habit, which form vivid and
broad green tufts, loaded with rich brown capsules, and which
abound both in the Alps and Polar regions. This is no doubt
indirectly due to the elevation of the region, and directly to
the sudden accessions of great heat and drought, which arc
the effects of a highly rarefied atmosphere, and which, though
strongly enough marked to check the development of Mosses
and Hepaticpe, arc not of sufficient duration to aifcct phueno-
gamic vegetation in the same degree.
b. On the Distribution of Indian Plants as 'influenced by
Geographical Position.
Hitherto we have solely considered the spread of plants in
India as influenced by climate, but geographical position is ac-
companied by such remarkable phenomena in vegetation, as
to indicate other influences, which demand some notice here.
The Floras of the frontier provinces of India, as we have re-
peatedly remarked, are identical witli those of the countries
that surround them, and are continuous with them, and that
this should be so stands to reason; but we sometimes sec
a decided affinity between the Floras of areas separated by
oceans, deserts, or mountain-chains, between which it is un-*
waiTantable to assume that a migration of the species com-
mon to both, has taken place since the interposition of the
barriers in question, and which further present many natural
characters in common, which neither migration (if conceded
to any amount) nor climate will account for. We have already